1. Field of the Invention
The present invention relates to a webbing take-up device in which a webbing belt that restrains a body of a vehicle occupant is taken up on a spool and is accommodated, and particular to a webbing take-up device which is equipped with a lock mechanism that regulates rotation of a spool in a direction in which the webbing is pulled out, at the time of a rapid deceleration of a vehicle.
2. Related Art
An acceleration sensor which constitutes a lock mechanism of a webbing take-up device disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2008-24284 is equipped with a hard ball placed on a mounting portion. When a vehicle is brought into a state of a rapid deceleration, the hard ball moves by inertia, and goes up a concave curved surface or inclined surface, which is formed on a mounting portion of a sensor frame, so as to push up a sensor pawl. Further, the sensor pawl pushed up by the hard ball pushes up a connecting pawl provided in a sensor gear such that the connecting pawl is engaged with a ratchet gear formed in an outer peripheral portion of a V-gear.
The V-gear is connected via a torsion shaft to a spool in a state of being not capable of rotating relative to the spool, and therefore, when the spool rotates in a pull-out direction in the state in which the connecting pawl engages with the ratchet gear of the V-gear, the sensor gear also rotates in the pull-out direction. When the sensor gear rotates in the pull-out direction, a pressing portion of the sensor gear presses against the lock pawl so as to cause the lock pawl to mesh with the ratchet gear of a lock base, thereby regulating rotation of the lock base in the pull-out direction as well as rotation of the spool in the pull-out direction. Thus, a webbing belt is restrained from being pulled out from the spool.
In the acceleration sensor as described above, a rotating shaft of the sensor pawl is inserted in a bearing hole of the sensor frame, and the sensor pawl is supported by the sensor frame in a rotatable manner. If the inner diameter of the bearing hole into which the rotating shaft is inserted is not larger than the outer diameter of the rotating shaft, the rotating shaft (and the sensor pawl) cannot be smoothly rotated.
However, by making larger the inner diameter of the bearing hole than the outer diameter of the rotating shaft, rattle occurs in the rotating shaft and the sensor pawl, thereby resulting in generation of abnormal noise.